Just found a blog by someone in my situation: struggling to get over an N friend
From what I’ve seen so far, she is a married woman with a platonic male friend who turned out to be a narcissist. No affair, no romance, but even as just a friendship, it sucked her in and was hard to get over. I’m very interested to see what she wrote over the years, and how she got through it:
http://elissestuart.wordpress.com/tag/narcissistic-personality-disorder/page/6/